Inductive power supply system with battery type detection

ABSTRACT

An inductive power supply system to wirelessly charge a remote device based on detected battery characteristics. The system includes an inductive power supply with a primary coil capable of inductively providing power to a secondary coil in a remote device. The inductive power supply and remote device include communication means for wirelessly communicating. The system further includes a remote device, having a battery with detectable battery characteristics. In operation, the remote device is capable of detecting the battery characteristics by applying a qualification charge to the battery. The inductive power supply system is capable of identifying the battery installed in the remote device by analyzing the detected battery characteristics. The inductive power supply system selects an appropriate charging algorithm based on the analyzed characteristics.

This application claims the benefit of U.S. Provisional Application No.61/030,749 filed Feb. 22, 2008.

BACKGROUND OF THE INVENTION

The present invention relates to wireless power and more particularly toa system and method for detecting remote device battery characteristicsand wirelessly supplying power to the remote device based on thedetected characteristics.

Charging of batteries with an inductive power supply is well-known.Inductive chargers for electric automobiles or small electric appliancessuch as toothbrushes have met some amount of success. Because inductivecharging does not require a physical connection between the battery andthe charger, the charging is considerably more convenient. However,there is room for improvement. One inconvenient aspect of conventionalinductive chargers is that they only charge one battery chemistry. Thatis, conventional inductive chargers use pre-determined hard codedcharging algorithms that do not adapt to account for different batterychemistries. Many devices accept batteries of multiple chemistries, butif the user does not employ the correct batteries for the particularinductive charger, the batteries will not charge efficiently, and mightnot charge at all.

Some wired battery chargers employ multiple charging algorithms toaccommodate devices that use different battery chemistries. For example,some flashlights accept either NiMH batteries or alkaline batteries.Wired battery chargers rely on a direct physical connection to thebatteries, which conventional inductive charging systems do not have, inorder to determine battery chemistry. For example, conventional wiredbattery chargers may determine remote device battery chemistry bydirectly sensing voltage, current or temperature during a qualificationcharge. These direct measurements may not be taken by a conventionalinductive charger, which makes determining the remote device batterychemistry and other remote device battery characteristics difficult.

SUMMARY OF THE INVENTION

The present invention provides an inductive power supply system andmethod for detecting remote device battery characteristics andwirelessly supplying power to the remote device based on the detectedcharacteristics. The system and method may accommodate a remote devicethat accepts batteries with various battery characteristics or multipleremote devices that operate using batteries with different batterycharacteristics.

One embodiment of the system includes an inductive power supply with aprimary circuit and primary coil as well as a remote device with asecondary coil, secondary circuit and battery. The primary circuitincludes a controller, a driver, a switch, and a communication means forcommunicating with the secondary circuit. The secondary circuit includesa rectifier, one or more sensors, a controller, a communication meansfor communicating with the primary circuit and a switch. The primarycoil and secondary coil inductively couple to wirelessly transfer powerfrom the inductive power supply to the remote device according to aselected wireless power charging algorithm. The wireless power chargingalgorithm is selected based on at least one characteristic of thebattery, which are detected by the secondary circuit. The remote devicemay also store and communicate data about the secondary device, such asnumber of batteries, expected cell types, reference voltage orcalibration information.

One embodiment of the method includes the steps of identifying theremote device, qualifying the battery of the remote device, selecting awireless power charging algorithm based on the battery qualification andwirelessly charging the remote device using the selected wireless powercharging algorithm.

The present invention provides a simple and effective system and methodfor wirelessly charging qualified batteries of a remote device,regardless of the particular type of rechargeable batteries employed bythe device. The ability for the inductive power supply system toeffectively detect various battery characteristics and employ anappropriate wireless power charging algorithm results in additionalflexibility and transparency for the user.

These and other objects, advantages, and features of the invention willbe readily understood and appreciated by reference to the detaileddescription of the current embodiment and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an inductive power supply system.

FIG. 2 is a block diagram of a primary circuit.

FIG. 3 is a block diagram of a secondary circuit.

FIG. 4 is a circuit diagram of a secondary circuit.

FIG. 5 is a picture of an inductive power supply system including aninductive power supply and a flashlight.

FIG. 6 is a block diagram of a flashlight.

FIG. 7 is a flowchart illustrating a method for detecting remote devicebattery characteristics and wirelessly supplying power to the remotedevice based on the detected characteristics.

FIG. 8 is a circuit diagram of an LED driver.

DESCRIPTION OF THE CURRENT EMBODIMENT

I. Overview

An inductive power supply system in accordance with an embodiment of thepresent invention is shown in FIG. 1, and generally designated 100. Theinductive power supply 102 includes a primary circuit 103 and a primarycoil 106. The remote device 104 includes a secondary coil 107, asecondary circuit 105 and a battery 108. The secondary circuit 105detects certain remote device battery characteristics and the system 100uses the detected characteristics to determine whether the batteryqualifies for charging. If the battery qualifies, an appropriatewireless power charging algorithm is selected and used to wirelesslycharge the battery. Although the present invention is generallydescribed in connection with a single battery, a person of ordinaryskill in the art would understand that the present invention may bemodified to operate with remote devices that have multiple batteries andbatteries that have multiple cells.

A method for detecting remote device battery characteristics andwirelessly supplying power from the inductive power supply to the remotedevice based on the detected characteristics in accordance with anembodiment of the present invention is illustrated in FIG. 7, andgenerally designated 700. The method includes identifying the remotedevice 702-708, qualifying the battery of the remote device includingselecting a wireless power charging algorithm based on the batteryqualification 710-714, and wirelessly charging the remote device usingthe selected wireless power charging algorithm 716-724. Other optionalsteps may be included, such as testing the capacity of the remote devicebattery 726-730.

The inductive power supply system 100 may include memory 203/317 capableof storing, among other things, wireless power supply chargingalgorithms and battery types. In one embodiment, each wireless powersupply charging algorithm is associated with at least one differentbattery type. In one embodiment, each wireless power supply chargingalgorithm is associated with at least one different battery chemistry.Further, the memory 203/317 may also store associations between batterycharacteristics and battery types. In one embodiment the primarycontroller 202 includes memory 203 and the secondary controller 316includes memory 317. In alternative embodiments, only one of thecontrollers includes memory or the memory is external to the controllersand may be included in the inductive power supply or the remote device.The information stored in memory may be used to permit the inductivepower supply 102 to efficiently power the remote device 104. Inapplications where the inductive power supply is capable of identifyingthe remote device, the memory may includes the unique resonant frequency(or pattern of frequencies) for various remote device 102, along withthe desired collection of associated information, such as maximum andminimum operating frequencies, current usage, number of batteries andsize of batteries. The memory may, however, include essentially anyinformation that may be useful to the inductive power supply 102 inoperating the remote device 104. For example, the memory may includeinformation regarding the wireless communication protocol of the remotedevice.

II. Inductive Power Supply

The present invention is suitable for use with essentially any inductivepower supply. Accordingly, the inductive power supply 102 will not bedescribed in detail. Suffice it to say that the inductive power supply102 includes a primary circuit 103 and a primary coil 106. The powersupply circuit 103 generates and applies alternating current to theprimary coil 106. As a result of the alternating current applied by thepower supply circuit 103, the primary coil 106 generates anelectromagnetic field. The power supply circuit 103 may be essentiallyany circuitry capable of supplying alternating current to the primarycoil 106 at the desired frequency or frequencies. For example, the powersupply circuit 103 may be the resonant seeking circuit of the inductivepower supply system disclosed in U.S. Pat. No. 6,825,620, which isentitled “Inductively Coupled Ballast Circuit” and issued Nov. 30, 2004,to Kuennen et al; the adaptive inductive power supply of U.S. Pat. No.7,212,414, which is entitled “Adaptive Inductive Power Supply” andissued May 1, 2007, to Baarman; the inductive power supply withcommunication of U.S. Ser. No. 10/689,148, which is entitled “AdaptiveInductive Power Supply with Communication” and filed on Oct. 20, 2003 toBaarman; the inductive power supply for wirelessly charging a LI-IONbattery of U.S. Ser. No. 11/855,710, which is entitled “System andMethod for Charging a Battery” and filed on Sep. 14, 2007 by Baarman;the inductive power supply with device identification of U.S. Ser. No.11/965,085, which is entitled “Inductive Power Supply with DeviceIdentification” and filed on Dec. 27, 2007 by Baarman et al; or theinductive power supply with duty cycle control of U.S. Ser. No.61/019,411, which is entitled “Inductive Power Supply with Duty CycleControl” and filed on Jan. 7, 2008 by Baarman—all of which areincorporated herein by reference in their entirety.

One embodiment of an inductive power supply system in accordance withthe present invention is pictured in FIG. 5. The inductive power supplysystem depicts an inductive power supply 504 and remote deviceflashlight 502. The inductive power supply 504 is contained within ahousing 501 having a surface 505 on which to place the remote deviceflashlight 502. The housing includes a power plug adapter 506 forplugging the inductive power supply into a wall outlet. The size, shapeand configuration of the housing 501 and surface 505 may vary. Forexample, the surface 505 may be flat and circular (as shown) or it maybe contoured to receive one or more remote devices 502. In oneembodiment, the housing may incorporate the inventive principles of U.S.Ser. No. 12/390,178 entitled “Magnetic Positioning for InductiveCoupling” to Baarman, which is being filed contemporaneously with thepresent application.

One embodiment of a primary circuit of an inductive power supply 102 isillustrated in FIG. 2, and generally designated 200. The primary circuit200 of the illustrated embodiment generally includes a primarycontroller 202, a driver circuit 204 and a switching circuit 206. Theprimary circuit 200 also includes a communication means forcommunicating with the remote device. In the illustrated embodiment,primary circuit 200 includes a wireless IR receiver 212 and a currentsensor 210. The current sensor 210 may be used to sense reflectedimpedance from the remote device, which effectively allows communicationover the inductive coupling. In some embodiments, a peak detectorreplaces or is used in conjunction with the current sensor 210. Inalternative embodiments, the receiver 212 or current sensor 210 may bedeleted. In other alternative embodiments, the wireless communicationmeans may replace one or both of the receiver 212 and current sensor210, for example, any of WIFI, infrared, Bluetooth, cellular or RFIDdevices may be implemented in the primary circuit 200. In operation, asdescribed above, the primary controller 202, driver circuit 204 andswitching circuit 206 apply alternating current to the primary coil 106to generate a source of electromagnetic inductive power at a selectedfrequency.

The primary coil 106 of the illustrated embodiment is a circular coil ofwire suitable for generating an electromagnetic field. In someapplications, the primary coil 106 may be a coil of Litz wire. Thecharacteristics of the coil may vary from application to application.For example, the number of turns, size, shape and configuration of thecoil may vary. Further, the characteristics of the wire may vary, suchas length, gauge and type of wire. Although described in connection witha coil of wire, the primary coil 106 may alternatively be essentiallyany structure capable of generating a suitable electromagnetic field. Inone embodiment, the primary coil 106 (or secondary coil 107) may bereplaced by a printed circuit board coil, such as a printed circuitboard coil incorporating the inventive principles of U.S. Ser. No.60/975,953, which is entitled “Printed Circuit Board Coil” and filed onSep. 28, 2007 by Baarman et al, and which is incorporated herein byreference in its entirety.

In certain embodiments of the present invention, the primary controller202 includes intelligence or programming for making decisions based onthe detected battery characteristics. For example, the secondary circuit105 may be programmed to communicate any detected batterycharacteristics or a determined battery type to the primary controller202. Once the primary controller 202 has access to the batterycharacteristics or determined battery type, an appropriate chargingalgorithm may be selected from memory or otherwise determined. In otherembodiments, the primary controller 202 does not receive and does nothave any specific intelligence or programming for making decisions basedon the detected battery characteristics. That is, the primary circuit103 merely receives messages that dictate the desired power level thatshould be provided. For example, the primary controller 202 may beprogrammed to ramp up power (subject to safety conditions) until itreceives a message from the secondary to stop. In another embodiment,the primary receives instructions from the secondary about whether toprovide more or less power. Alternatively, the primary controller mayreceive specific instructions to transmit at a particular operatingfrequency or to adjust its operating frequency in a particular manner.In another embodiment, the primary controller may receive instructionsfrom the remote device 104 to reconfigure the primary circuit 103 tochange the resonant frequency based on determinations made by thesecondary circuit 105 using detected battery characteristics. In yetanother embodiment, the primary controller may receive instructions tochange the input voltage to adjust the inductive power output.

The primary controller 202 may optionally be programmed with additionalfeatures. For example, in one embodiment, the primary controller 202 isprogrammed to identify remote devices using the inventive principlesdescribed in U.S. Ser. No. 11/965,085, which was previously incorporatedby reference. The remote device ID may include information about theremote device battery. Alternatively, information about the remotedevice battery may be accessed using the remote device ID as a key to alook up table on the inductive power supply. For example, theinformation may indicate whether the remote device is within the powerrange of the inductive power supply. Or, the information may include thetypes and sizes of batteries accepted by the remote device. For example,a particular remote device may only be capable of receiving two AAbatteries due to geometric constraints. The

Optionally, the inductive power supply may include an LED scheme toindicate charging status. When the LED is off, no device is present. Ifthe LED is solid, a remote device is detected. A flashing LED indicatesthat the battery is bad or unqualified. A breathing LED indicates thatthe remote device is currently being charged. A color or intensitychange in the LED indicates that charging is complete. A person ofordinary skill in the art would understand that additional or differentschemes may be implemented to indicate charging status to the user.

III. Remote Device

The present invention is suitable for use with a wide variety of remotedevices of varying designs and constructions. The present invention mayaccommodate remote devices that accept various battery types. Batterytype is used generally to distinguish between batteries based on one ormore battery characteristics of the batteries. For example, batterieswith different battery types may have different battery chemistry,battery cells, battery capacity, battery size, battery shape, batteryvoltage characteristics, battery current characteristics, batterytemperature characteristics, battery terminal layouts, cycles, span ofcycles, or any combination thereof. The scope of the term battery typemay differ depending on the embodiment. For example, in someembodiments, batteries may be different battery types even if they onlydiffer by a single battery characteristic. In other embodiments,batteries may be the same battery type even if they only share a singlebattery characteristic. The term battery is used throughout thisapplication in the singular, but a person of ordinary skill in the artwould understand that the battery could be a battery pack and thatbattery characteristics or type of battery may refer to battery packcharacteristics or the type of battery pack.

The present invention may accommodate individually charging multipleremote devices that operate using batteries with different batterycharacteristics. In alternative embodiments, multiple remote deviceswith similar battery characteristics may be charged simultaneously. Itis anticipated that these various remote devices will require power atvarying frequency and will have different power requirements.

As noted above, the remote device 104 generally includes a secondarycoil 107, a secondary circuit 105 and a battery 108. The remote device104 is illustrated representatively in the drawings, but it may beessentially any device or component that operates on batteries. Forexample, a flashlight (as shown in FIG. 5), cell phone, personal digitalassistant, digital media player or other electronic device that iscapable of utilizing a rechargeable battery.

The secondary coil 107 of the illustrated embodiment is a circular coilof wire suitable for generating electricity when in the presence of avarying electromagnetic field. As shown, the secondary coil 107 maycorrespond in size and shape to the primary coil 106. For example, thetwo coils 106 and 107 may have substantially equal diameters. In someapplications, the secondary coil 107 may be a coil of Litz wire. As withthe primary coil 106, the characteristics of the secondary coil 107 mayvary from application to application. For example, the number of turns,size, shape and configuration of the secondary coil 107 may vary.Further, the characteristics of the wire may vary, such as length, gaugeand type of wire. Although described in connection with a coil of wire,the secondary coil 107 may alternatively be essentially any structurecapable of generating sufficient electrical power in response to theintended electromagnetic field.

A secondary circuit in accordance with an embodiment of the presentinvention is shown in FIG. 3, and generally designated 300. Theillustrated secondary circuit 300 includes a secondary controller 316, arectifier 304, a switch 306, a current sensor 310, a temperature sensor312 and a voltage sensor 314. The secondary circuit 300 also includes acommunication means for communicating with the inductive power supply102. The illustrated embodiment includes a signal resistor 318 forcommunicating using reflected impedance over the inductive coupling anda wireless transmitter 320. In alternative embodiments, the signalresistor 318 or wireless transmitter 320 may be deleted. In alternativeembodiments, other wireless communication means may replace one or bothof the wireless transmitter 320 and signal resistor 318. For example,any of a WIFI, infrared, Bluetooth, cellular or RFID device may be usedto wirelessly communicate with the inductive power supply 102.

In operation, the illustrated secondary circuit 300 is programmed todetect various battery characteristics, such as battery voltage, batterycurrent, battery temperature or a combination thereof. The secondarycircuit uses the detected characteristics to determine whether thebattery qualifies for charging and if it does, an appropriate chargingalgorithm is selected by the secondary controller 316. In alterativeembodiments, the intelligence may be spread across the primary circuitand secondary circuit, as described above. For example, as noted above,in one embodiment, the secondary circuit 300 may communicate thedetected battery characteristics to the inductive power supply so thatan appropriate charging algorithm may be selected by the primary circuit103.

For purposes of disclosure, one embodiment of a secondary circuit isshown in FIG. 4, and generally designated 400. In the embodimentillustrated in FIG. 4, the secondary circuit 400 generally includes asecondary controller 428, rectifier 414 (or other components forconverting AC power to DC), a low voltage power supply 412 that scalesthe received power to operate the secondary controller 428, conditioningcircuitry 416, 426 to remove ripple in the signal, current sensor 418,voltage sensor 422, temperature sensor 434, switch 420, a signalresistor 432 and an optional wireless transmitter 430. In operation, therectifier 414 converts the AC power generated in the secondary coil 107to DC power, which is typically needed to charge the battery 108.Alternatively, multiple secondary coils receiving power of differentphases can be used to reduce the ripple voltage. This is referenced inApplication 60/976,137, entitled “Multiphase Inductive Power SupplySystem” filed Sep. 9, 2007 to Baarman et al, which is hereinincorporated by reference. Multiple primary coils may be desired totransmit power on different phases in such an embodiment. In alternativeembodiments the rectifier may be unnecessary and AC power may beconditioned to be used to power the load.

The secondary circuit includes a battery characteristic detection systemfor detecting one or more characteristics of a battery that either aloneor in combination, directly or indirectly, are indicative of the type ofbattery installed in the remote device or the wireless power chargingalgorithms capable of charging that battery. A characteristic is to beconsidered indicative of the type of battery even if othercharacteristics must be considered to identify the battery type.Further, a characteristic is to be considered indicative of the type ofbattery even if the characteristic only allows the battery type to benarrowed to a list of possible battery types. In the current embodiment,the battery characteristic detection system includes a current sensor418, a voltage sensor 428, and a temperature sensor 434. The currentsensor 418 detects the amount of current in the received power andprovides that information to the secondary controller 428. The voltagesensor 422 detects the amount of voltage in the received power andprovides that information to the secondary controller 428. Thetemperature sensor 434 detects the temperature and provides thatinformation to the secondary controller 428. Although the illustratedembodiment includes a voltage sensor 422, a current sensor 418 and atemperature sensor 434, alternative embodiments need not include allthree. One or more sensors, detectors, or other devices or systems thatassess, detect, or sense battery characteristics may replace orsupplement the illustrated battery characteristic detection system. Inthe current embodiment, by sensing the voltage, current and temperatureof the battery, the inductive power supply system 100 can determine,among other things, the battery type.

The secondary controller 428 may be essentially any type ofmicrocontroller. In the illustrated embodiment, the secondary controller428 is an ATTINY2MV-10MU microcontroller. The secondary controller 428generally includes an analog to digital converter, and is programmed toprocess the voltage, current and temperature readings in order todetermine if the battery qualifies as chargeable. The microprocessor mayalso include other code unrelated to battery qualification. Furthermore,the ability to have a controller or other intelligence in the remotedevice allows characterization of various battery characteristics. Forexample, the secondary may make determinations about battery type andbattery life by tracking cycles, span of these cycles and the ability tohold a charge. It also allows coulombs counting, which is a method knownin the art for accurate energy use and expenditure calculations.Thresholds may be set for battery end of life tracking on almost anytype of battery.

In one embodiment, signal resistor 432 may be used to send informationto the primary controller 310. The use of a signal resistor 432 toprovide communication from the secondary to the primary was discussed inU.S. patent application Ser. No. 11/855,710, which was previouslyincorporated by reference. The signal resistor 432, when shunted, sendsa communication signal that signifies an over-current or over-voltagestate. When the resistor is shunted, the current or peak detector on theprimary circuit 103 is able to sense the over-voltage/over-currentcondition and act accordingly. The signal resistor 432 of the presentinvention may be shunted systematically to communicate additional datato the primary controller 310. For example, a stream of data couldrepresent the detected current, detected voltage, detected temperature,detected battery chemistry, or merely provide an instruction to theprimary circuit 103 to adjust the inductive power supply. Alternatively,the signal resistor could be removed and a different communication meansentirely could be used to wirelessly communicate with the primarycircuit 103.

Use of a wireless transmitter or transceiver was previously described inU.S. Patent Application Publication US 2004/130915A1 to Baarman, whichwas previously incorporated by reference. Specifically, the use of WIFI,infrared, Bluetooth, cellular or RFID were previously discussed as waysto wirelessly communicate data between a remote device to an inductivepower supply. Further, communication using the induction coils and apower line communication protocol was discussed. Any of these methods oftransmitting data could be implemented in the present invention in orderto transfer the desired data from the remote device to the inductivepower supply.

In the illustrated embodiment, charging is controlled by the secondarycircuit. The primary circuit 103 provides wireless power and respondsappropriately to control signals from the secondary circuit 105. In thecurrent embodiment, communications happens at pre-defined, continuousintervals while power is being transferred. For example, communicationmay occur in the form of trip points or error signals.

A remote device in accordance with one embodiment of the presentinvention is shown in FIG. 6, and generally designated 600. The remotedevice 600 includes Plitz coil 602, a DC/DC converter, a chargercontroller 606, a battery 609, an LED driver 608 and an LED assembly610. As noted above with respect to the primary coil, either or both ofthe primary coil 602 and secondary coil 604 may be replaced by a printedcircuit board coil, such as a printed circuit board coil incorporatingthe inventive principles of U.S. Ser. No. 60/975,953, entitled “PrintedCircuit Board Coil” which was previously incorporated by reference.Further, either coil 602, 604 may be replaced with a standard litz wirecoil, which in some circumstances grants additional transfercapabilities.

Flashlight LEDs typically run at a relatively low voltage range, around3.6V. The driver takes a voltage in a range and outputs 3.6V for theLED. An exemplary driver is shown in FIG. 8. For example, two nearlydepleted AA batteries might give 0.9V each, or 1.8V total. Four new AAbatteries might give 1.5V each, or 6V total. The LED driver convertseither of these voltages to the 3.6V required by the LED withoutsignificant power loss.

A DC/DC converter regulates the amount of current and is particularlyuseful in applications where the inductive power supply is doing lessadjustment. An inductive power supply may supply power to multipleremote devices provided the remote devices have a mechanism to regulatethe amount of power received, such as by using a DC/DC converter.

Optionally, the remote device may include an LED and LED scheme toindicate charging status. When the LED is off, no inductive power supplyis present. If the LED is solid, the remote device is receiving power. Apre-determined number of LED flashes indicates that the battery is bad.A breathing LED indicates that the remote device is currently beingcharged. A color or intensity change in the LED indicates that chargingis complete. A person of ordinary skill in the art would understand thatadditional or different schemes may be implemented to indicate chargingstatus to the user. Further, inclusion of an LED and LED scheme oneither or both of the inductive power supply and remote device isoptional.

IV. Operation

General operation of the inductive power supply 102 and remote device104 is described in connection with FIG. 7. In particular, a method fordetecting remote device battery characteristics and wirelessly supplyingpower from the inductive power supply to the remote device based on thedetected characteristics in accordance with an embodiment of the presentinvention is illustrated in FIG. 7, and generally designated 700. Themethod includes optionally identifying the remote device 702-708,qualifying the battery of the remote device including selecting acharging algorithm based on the battery qualification 710-714, andwirelessly charging the remote device using the selected chargingalgorithm 716-724. Other optional steps may be included, such as testingthe capacity of the remote device battery 726-730.

The optional remote device identification may be accomplished usingessentially any method. In one embodiment, the inductive power supplyperiodically transmits an identification charge for a pre-selectedamount of time. If a remote device with a secondary coil is present andaligned during the identification charge, the remote device sends apre-encoded identification string back to the primary. As discussedabove, the communication channel could be near field, IR, RF oressentially any other suitable communication channel. In an alternativeembodiment, the remote device may include an identification capacitorthat creates resonance at a specific frequency. The inductive powersupply sweeps a range of identification frequencies seeking resonance.The frequency at which resonance is found may be used to identify theremote device using a look up table on the primary controller. Remotedevice identification potentially increases safety because metal slugsor other foreign devices will not transmit the proper ID and theinductive power supply will not continue to provide power. Remote deviceidentification is optional though, and embodiments of the presentinvention need not include remote device identification in order tofunction.

Battery qualification or battery wireless power charging algorithmselection 710-714 includes detecting battery characteristics, analyzingthe known and detected battery characteristics to determine whether thebattery qualifies for charging, and selecting an appropriate chargingalgorithm either directly based on the known and detected batterycharacteristics or indirectly based on the known and detected batterycharacteristics. Indirect qualification may include additionalanalyzing, such as categorizing the battery type of the battery based onthe raw battery characteristics. Direct qualification may forgo thisstep in favor of selecting a charging algorithm based on the raw batterycharacteristics. In the current embodiment, qualification is primarilydependent on battery chemistry. Unknown chemistries do not charge712-714, while known chemistries are charged based on their batterychemistry 712-716. In an alternative embodiment, battery qualificationincludes categorizing the battery into one of a plurality of generalpower class, each associated with a different charging algorithm.Although the ultimate selection of a wireless power charging algorithmmay not be based on raw battery characteristics and instead based on aproduct of additional analyzing, such as a categorization into batterytype or power class, it should be understood that this is ultimatelystill a selection based on a battery characteristic, either known,detected, or both.

In operation, the secondary controller 428 is programmed to determine ifthe battery 108 qualifies for charging. Some battery information may beknown based on the physical limitations of the remote device 104. Forexample, the type and size of batteries that fit into the remote deviceis typically set during manufacture by the geometric configuration ofthe remote device. Additionally, the remote device may include cellinformation, including the number of cells. The number of cells andnumber of batteries may be interrelated are in some applications theterms may be used interchangeably. As noted above, this information maybe directly or indirectly stored in memory. That is, specificinformation related to a specific remote device may be stored in thememory, or a look-up table may be stored in memory which may be accessedusing a remote device ID. This information may be factored in to thebattery qualification decision. For example, most remote devices cannotoperate on both 1.5V AAs and 3.7V LiIon batteries.

Not all remote devices are limited by geometry, some may be capable ofaccepting batteries of different shapes and sizes. To account for that,the secondary controller 428 may be programmed to narrow down thebattery possibilities. For example, the secondary controller 428 maydetermine the number of battery cells and the starting voltage of eachof the cells. If the starting voltage is greater than a pre-definedthreshold for that number of cells then the battery may be identified asa LiIon battery. If the starting voltage is less than a differentpre-defined threshold for that number of cells the battery may beidentified as non-chargeable because of an internal short or overdepletion. If the starting voltage is between the two thresholds, thebattery may be identified as a non-LiIon battery, such as NiMH orAlkaline.

In addition to using known, pre-defined battery characteristics, unknownbattery characteristics may be actively measured. For example, by usingthe inductive power supply to feed a qualification charge to the remotedevice battery, the change in voltage may be measured and used tocharacterize the battery. The qualification charge may be any suitablecharge that assists in the identification of battery characteristics. Inthe current embodiment, the qualification charge is a low current,1/400^(th) of the rated battery capacity which is approximately 20milliamps. Other steps may be taken to help characterize the battery.For example, a change in current, voltage and/or temperature in responseto the qualification charge may be monitored.

In the current embodiment, the secondary circuit 400 monitors the changein voltage in response to the qualification charge. If the change involtage is above a certain threshold, the internal resistance of thebatteries is too high and the batteries are deemed bad ornon-rechargeable. If the change in voltage is below a certain thresholdthe batteries are also deemed bad, likely because they are shortedinternally. If the change in voltage is between the two thresholds, thebatteries are deemed chargeable and the inductive power supply proceedsto full charge rate.

The voltage is monitored as the full charge rate is employed. Similarthresholds to those employed during the qualification charge may bemonitored while charging at the full rate. Passing one of the thresholdsis a substantial indication that the battery is near the end of itslife. Further, battery capacity may be determined by monitoring thecharge rate and battery voltage. If the battery voltage passes apredetermined threshold, the batteries may be deemed damaged or near theend of their life.

Additional information may be provided by the remote deviceconfiguration like the number of cells and typical operation withvarious batteries. For example, points on a curve for each type ofbattery may be stored in memory on the secondary device. A person ofordinary skill in the art would understand how these curves can be usedas patterns to recognize battery types, battery life, diagnostics andother pattern comparison information.

Once full charging rate is reached, any number of battery chemistrycharging profiles may be employed. The most common difference incharging algorithm is between nickel based batteries, which utilize anegative delta V algorithm and Li Ion batteries, which transition from aconstant current a constant voltage after a current lower limit isreached. Many other battery chemistry charging profiles are known andmay be implemented in the present invention. For example, a particularchemistry charging profile may be included for alkaline rechargeablebatteries that is different from the Nickel based and LiIon chargingprofiles. In the current embodiment, the secondary circuit candistinguish between Alkaline, NiMH, NiCad, CZn and Li Ion batteries. Inalternative embodiments, the secondary controller may be able todistinguish between additional, different or fewer battery chemistries.

Battery capacity may be determined by monitoring the charge rate andbattery voltage. If the battery voltage passes a pre-determinedthreshold, the batteries may be deemed damaged or near the end of theirlife.

The above description is that of the current embodiment of theinvention. Various alterations and changes can be made without departingfrom the spirit and broader aspects of the invention.

The invention claimed is:
 1. An inductive power supply system comprising: an inductive power supply including a primary circuit and a primary for wirelessly transferring power; a remote device separable from said inductive power supply, said remote device including a secondary for wirelessly receiving power from said inductive power supply, a battery having a battery type, and a secondary circuit that includes a battery characteristic detection system for detecting a characteristic of said battery indicative of said battery type, said characteristic of said battery including at least one of a battery voltage characteristic, a battery current characteristic, and a battery temperature characteristic; a memory located in at least one of said inductive power supply and said remote device, said memory including a plurality of wireless power charging algorithms; a communication system for wireless communication between said remote device and said inductive power supply; a controller adapted to communicate with said memory, said controller located in at least one of said inductive power supply and said remote device, wherein said controller is programmed to select a wireless power charging algorithm from said plurality of wireless power charging algorithms in said memory based at least in part on said detected battery characteristic indicative of said battery type; and wherein said primary wirelessly transfers power from said inductive power supply to said remote device according to said selected wireless power charging algorithm.
 2. The inductive power supply system of claim 1 wherein said battery is replaceable with a different battery having a different battery type.
 3. The inductive power supply system of claim 2 wherein said controller selects a different wireless power charging algorithm for said different battery based at least in part on said battery characteristic detection system detecting a characteristic of said different battery indicative of a different battery type.
 4. The inductive power supply system of claim 1 wherein said memory includes a plurality of battery types, wherein each of said battery types is associated with one or more wireless power charging algorithms.
 5. The inductive power supply system of claim 1 wherein said inductive power supply selects said wireless power charging algorithm based at least in part on at least one of 1) said detected battery characteristic; and 2) a determined battery type communicated from said remote device to said inductive power supply, said determined battery type determined by said controller based at least in part on said detected battery characteristic.
 6. The inductive power supply system of claim 1 wherein said remote device selects said wireless power charging algorithm based at least in part on at least one of 1) said detected battery characteristic; and 2) a determined battery type, said determined battery type determined by said controller based at least in part on said detected battery characteristic.
 7. The inductive power supply system of claim 1 wherein said communication system includes: a remote device communication system for wirelessly communicating with said inductive power supply including at least one of a signal resistor for communicating using said secondary and a wireless transmitter; and an inductive power supply communication system for wirelessly communicating with said remote device including at least one of a current sensor for communicating using said primary and a wireless receiver.
 8. The inductive power supply system of claim 1 wherein said controller is programmed to select said wireless power charging algorithm from said plurality of wireless charging algorithms based on a comparison between said detected battery characteristic and a threshold.
 9. The inductive power supply system of claim 1 wherein said controller is programmed to supply a qualification charge to said battery, wherein said detected battery characteristic changes in response to said qualification charge, and wherein said controller selects said wireless charging algorithm from said plurality of wireless charging algorithms based on said change in said detected battery characteristic.
 10. A remote device separable from an inductive power supply, said remote device comprising: a secondary for wirelessly receiving power from said inductive power supply; a battery having a battery type; a battery characteristic detection system for detecting a characteristic of said battery indicative of said battery type of said battery, said characteristic of said battery including at least one of a battery voltage characteristic, a battery current characteristic, and a battery temperature characteristic; a communication system for wirelessly communicating with said inductive power supply; a controller adapted to communicate with a memory including a plurality of wireless power charging algorithms, said controller programmed to at least one of: 1) select a wireless power charging algorithm from said plurality of wireless power charging algorithms in said memory based at least in part on said detected battery characteristic indicative of said battery type detected by said battery characteristic detection system; and 2) communicate said detected battery characteristic to said inductive power supply for use in selecting a wireless power charging algorithm; wherein said secondary wirelessly receives power from said inductive power supply according to said selected wireless power charging algorithm.
 11. The remote device of claim 10 wherein said battery is replaceable with a different battery having a different battery type.
 12. The remote device of claim 11 wherein said controller selects a different wireless power charging algorithm for said different battery based at least in part on said battery characteristic detection system detecting a characteristic of said different battery indicative of a different battery type.
 13. The remote device of claim 10 wherein said memory includes a plurality of battery types, wherein each of said battery types is associated with one or more wireless power charging algorithms.
 14. The remote device of claim 10 wherein said communication system communicates to said inductive power supply at least one of 1) said detected battery characteristic; and 2) a determined battery type, said determined battery type determined by said controller based at least in part on said detected battery characteristic.
 15. The remote device of claim 14 wherein said controller selects said wireless power charging algorithm based at least in part on said determined battery type.
 16. The remote device of claim 10 wherein said communication system for wirelessly communicating with said inductive power supply includes at least one of a signal resistor for communicating using said secondary and a wireless transmitter.
 17. An inductive power supply separable from a remote device, said inductive power supply comprising: a primary for wirelessly transferring power to said remote device; a communication system for receiving from said remote device a detected battery characteristic indicative of a battery type, said characteristic of said battery including at least one of a battery voltage characteristic, a battery current characteristic, and a battery temperature characteristic; a memory including a plurality of wireless power charging algorithms; a controller adapted to communicate with said memory, said controller programmed to select a wireless power charging algorithm from said plurality of wireless power charging algorithms in said memory based at least in part on said detected battery characteristic indicative of said battery type; wherein said primary wirelessly transfers power from said inductive power supply to said remote device according to said selected wireless power charging algorithm.
 18. The inductive power supply of claim 17 wherein said memory includes a plurality of battery types, wherein each of said battery types is associated with one or more wireless power charging algorithms.
 19. The inductive power supply of claim 17 wherein said communication system for wirelessly communicating with said remote device includes at least one of a current sensor for communicating using said primary and a wireless receiver.
 20. The inductive power supply of claim 17 wherein said controller is programmed to select said wireless power charging algorithm from said plurality of wireless charging algorithms based on a comparison between said detected battery characteristic and a first threshold.
 21. The inductive power supply of claim 20 wherein in response to said detected battery characteristic being greater than said first threshold, said controller selects said wireless charging algorithm for a lithium ion battery.
 22. The inductive power supply of claim 20 wherein based on said detected battery characteristic being between said first threshold and a second threshold, said controller selects said wireless charging algorithm for a nickel metal hydride battery.
 23. The inductive power supply of claim 20 wherein based on said detected battery characteristic being less than said first threshold, said controller determines that said battery is non-chargeable.
 24. The inductive power supply of claim 20 wherein said first threshold is based on a number of cells present in said battery.
 25. The inductive power supply of claim 17 wherein said controller is programmed to supply a qualification charge to said battery, wherein said detected battery characteristic changes in response to said qualification charge, and wherein said controller selects said wireless charging algorithm from said plurality of wireless charging algorithms based on said change in said detected battery characteristic.
 26. A method for transferring power from an inductive power supply to a remote device adapted to operate with a plurality of different types of batteries, said method comprising the steps of: detecting a characteristic of a battery installed in said remote device, wherein said characteristic of said battery is indicative of a battery type, said characteristic of said battery including at least one of a battery voltage characteristic, a battery current characteristic, and a battery temperature characteristic; selecting a wireless power charging algorithm based at least in part on said detected battery characteristic indicative of said battery type; wirelessly transferring power from said inductive power supply to said remote device according to said selected wireless power charging algorithm.
 27. The method of claim 26 wherein said selecting said wireless power charging algorithm includes comparing said detected battery characteristic to a first threshold.
 28. The method of claim 27 wherein in response to said detected battery characteristic being greater than said first threshold, said wireless power charging algorithm for a lithium ion battery is selected.
 29. The method of claim 27 wherein in response to said detected battery characteristic being between said first threshold and a second threshold, said wireless charging algorithm for a nickel metal hydride battery is selected.
 30. The method of claim 27 wherein in response to said detected battery characteristic being less than said first threshold, determining that said battery is non-chargeable.
 31. The method of claim 27 wherein said first threshold is based on a number of cells present in said battery.
 32. The method of claim 26 further comprising supplying a qualification charge to said battery, wherein said detected battery characteristic changes in response to said qualification charge, and wherein said selecting said wireless charging algorithm from said plurality of wireless charging algorithms is based on said change in said detected battery characteristic. 